Modification of the ACI 318 Design Method for Slab-Column Connections Subjected to Unbalanced Moment

2014 ◽  
Vol 17 (10) ◽  
pp. 1469-1480
Author(s):  
Kyoung-Kyu Choi ◽  
Dong-Woo Shin ◽  
Hong-Gun Park
Keyword(s):  
Design Method ◽  
Punching Shear ◽  
Vertical Shear ◽  
Strength Prediction ◽  
Shear Stresses ◽  
Test Results ◽  
Reasonable Accuracy ◽  
Proposed Model ◽  
Extensive Test ◽  
Flexural Reinforcement

In the ACI 318–11 design method for slab-column connections subjected to unbalanced moment, the contribution factors assigning the proportion of the connection unbalanced moment to be resisted by the slab flexural reinforcement and by eccentric vertical shear stresses are prescribed by only considering the aspect ratio of columns. However, the validity of the prescribed contribution factors have not been completely verified by extensive test results, and the strength prediction by the design method using the contribution factors does not agree well with existing test results. In the present study, a modified strength model was proposed without prescribing the contribution factors. In the proposed model, the contribution of flexural moment is directly calculated using the slab reinforcement ratio, and the contribution of eccentric shear is calculated based on the conventional eccentric shear stress model. The proposed method was verified by comparing its prediction with existing test results. The results showed that the proposed method predicts the test results with reasonable accuracy, and it corresponds with the fundamental mechanics of the punching shear of slab-column connections as investigated in previous studies.

scholarly journals A Local Design Method for Pile Foundations

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Nunzia Letizia ◽  
Chiara Iodice ◽  
Alessandro Mandolini
Keyword(s):  
Design Method ◽  
Load Test ◽  
Preliminary Design ◽  
Test Results ◽  
Reasonable Accuracy ◽  
Case Histories ◽  
Original Design ◽  
Settlement Ratio ◽  
Pile Load Test ◽  
The One

The work at hand attempts to propose a local pile design method based on pile load test results for a reference site. Such LPDM is simply based on the identification of three dimensionless quantities, such as the capacity ratio CR, the stiffness ratio SR, and the group settlement ratio Rs. To prove the LPDM reliability, experimental data collected during years in the Neapolitan area (Italy) have been used to obtain the abovementioned coefficients. Then, LPDM has been applied, as a preliminary design method, to three well-documented case histories applying capacity and settlement-based design (CBD and SBD) approaches. The satisfactory agreement between the geometry in the original design of piles and the one obtained by applying the LPDM proves that the proposed methodology may be very helpful for preliminary design, allowing for reasonable accuracy while requiring few hand calculations.

ANALYSIS OF RESEARCH AND DESIGN MODELS FOR THE PUNCHNING SHEAR OF FLAT RC SLABS

2010 ◽  
Vol 2 (3) ◽  
pp. 93-100
Author(s):  
Gediminas Marčiukaitis ◽  
Remigijus Šalna
Keyword(s):  
Shear Strength ◽  
Theoretical Calculations ◽  
Theoretical Models ◽  
Complex Stress ◽  
Complex Stress State ◽  
Punching Shear ◽  
Shear Stresses ◽  
Test Results ◽  
Design Models ◽  
The Difference

The paper presents the review and analysis of the existing methods and models for calculating punching shear strength. The analysis of the existing design methods has showed that there is no unified theory about calculating punching shear strength. The models are similar in the way that fictitious shear stresses act in the fictitious shear area and are mainly obtained from the test results that may differ in their values. Therefore, the difference between the results obtained employing various calculation methods can be as high as 1,37 times, whereas the difference between the results of theoretical calculations and test research may vary up to 1,8 times. These facts clearly demonstrate that punching shear phenomena are not completely analyzed and require additional researches. The paper also proposes an in-deep analysis of famous analytical punching shear calculation models suggested within the last 50 years like Kinnunen and Nylander (1960), Moe (1961), Breastrup et al. (1976), Georgopoulos (1989), Broms (1990), Hallgren (1998), Menetrey (2002) and Theodorakopoulos (2002). The development of the above mentioned design models, the main assumptions and an algorithm for calculating punching shear strength are discussed in the article. The review of the existing models for calculating punching shear strength has also revealed that two main model types can be distinguished: type 1 – failure occurs when the compression zone is cut by shear and compression stress; type 2 – failure occurs when tensile stresses in concrete punching cone exceeds its tensile strength. A comparison between theoretical models and test results performed by different authors demonstrate that more accurate results can be obtained by calculating punching shear strength using the first types of models. The analysis has revealed it is purposeful to search for more effective reinforcing methods that can change the character of failure from brittle to plastic. A more effective replacement of reinforcement and the behaviour of concrete taking into account complex stress state in the failure zone should be applied.

scholarly journals Punching shear in flat slabs by strut and tie model

2021 ◽  
Vol 14 (5) ◽  
Author(s):  
Ricardo José Carvalho Silva ◽  
Dênio Ramam Carvalho de Oliveira ◽  
Nívea Gabriela Benevides de Albuquerque ◽  
Thiago Andrade Gomes ◽  
Aaron Kadima Lukanu Lwa Nzambi
Keyword(s):  
Shear Resistance ◽  
Punching Shear ◽  
Strength Prediction ◽  
Design Codes ◽  
Test Results ◽  
Main Design ◽  
Strut And Tie ◽  
Flat Slabs ◽  
The One ◽  
Strut And Tie Model

Abstract Research on behavior of flat slabs under punching shear, performed by Kinnunen, Regan and Muttoni influenced the main design recommendations. Meanwhile, studies about strut and tie model developed by Schlaich for beams, deep beams and corbels also influenced these design codes. This work aimed to adapt the strut and tie model for the punching shear resistance analysis in flat slabs. The punching shear resistance of 30 flat slabs verified through strut and tie model was compared to the one designed following Brazilian, American and European codes recommendation. Subsequently, this same model was validated by comparing the test results of 32 flat slabs. The strut and tie model results, when compared with the test results, showed a better average than those from codes, and the modified strut and tie model can become an alternative for punching shear strength prediction.

Analytical Study on Biaxial Strength of Structural Ceramics under Tension-Compression Condition

2005 ◽  
Vol 297-300 ◽  
pp. 40-46
Author(s):  
Satoshi Hanawa ◽  
Masahiro Ishihara ◽  
Yoshinobu Motohashi
Keyword(s):  
Pore Size ◽  
Structural Design ◽  
Design Method ◽  
Safety Margin ◽  
Fracture Model ◽  
Strength Prediction ◽  
Uniaxial Tensile ◽  
Proposed Model ◽  
Microstructure Parameters ◽  
Compression Condition

In the structural design of ceramics components especially for graphite materials, it is important to apply the realistic fracture model in the design method so as to reduce the large safety margin. In this study, we proposed the multiaxial strength model by expanding the microstructure based brittle fracture model applicable to both uniaxial tensile and compressive stress conditions. The advantage of the model is a treatment of the microstructural information such as grain size, pore size and pore size distribution. The proposed model was applied to biaxial strength prediction of near isotropic nuclear graphite using grain/pore related microstructure parameters. Predicted results were compared with biaxial strength data, and it was found that the proposed fracture model showed fairly good strength prediction.

scholarly journals Punching shear in reinforced concrete flat slabs with hole adjacent to the column and moment transfer

2014 ◽  
Vol 7 (3) ◽  
pp. 414-467 ◽  
Author(s):  
D. C. Oliveira ◽  
R. B. Gomes ◽  
G. S. Melo
Keyword(s):  
Reinforced Concrete ◽  
Reinforcement Rate ◽  
Load Test ◽  
Punching Shear ◽  
Test Results ◽  
Flat Slab ◽  
Flat Slabs ◽  
Flexural Reinforcement ◽  
Hole Dimension ◽  
The Moment

The structural behavior and the ultimate punching shear resistance of internal reinforced concrete flat slab-column connections, with one hole adjacent to the column, with or without flexural moment transfer of the slab to the column was investigated. Main variables were: the existence whether or not hole, flexural reinforcement layout and ratio, the direction and sense of the moment transferred and the eccentricity of the load (M (moment transferred to column) / V (shear)) ratio at the connection - 0,50 m or 0,25 m. Seven internal slab-column joining were tested and ultimate loads, cracking, deflections, concrete and reinforcement strains were analyzed. The existence of hole adjacent to the smaller column dimension, the hole dimension, flexural reinforcement rate and placing, the variation of relation Mu/Vu in function of the load, and, than, of eccentricity of the load, influenced the slabs behavior and rupture load. Test results were compared with the estimations from CEB-FIP/MC1990 [7], EC2/2004 [12], ACI-318:2011 [1] and NBR 6118:2007 [5]. ACI [1] and EC2 [12] presented most conservative estimates, although have presented some non conservative estimates. Brazilian NBR [5], even though being partly based in EC2 [12], presented smaller conservative estimates and more non conservative estimates. A modification on all codes is proposed for taking in account the moment caused by the eccentricity at the critical perimeter for slabs with holes.

scholarly journals Nonlinear Finite Element Analysis Formulation for Shear in Reinforced Concrete Beams

2019 ◽  
Vol 9 (17) ◽  
pp. 3503 ◽  
Author(s):  
Sang-Ho Kim ◽  
Sun-Jin Han ◽  
Kang Kim
Keyword(s):  
Shear Stress ◽  
Reinforced Concrete ◽  
Stress Function ◽  
Shear Stresses ◽  
Rc Beams ◽  
Test Results ◽  
Proposed Model ◽  
Load Displacement ◽  
Shear Stress Function ◽  
Column Element

This study suggests a novel beam-column element formulation that utilizes an equilibrium-driven shear stress function. The beam shear is obtained from the bi-axial states of micro-planes, through matrix condensation and zero vertical traction assumptions. This properly remedies the shear stiffening of a one-dimensional beam-column element, keeping its degrees of freedom to a minimum. For verification of the proposed method, a total of seven shear test results of reinforced concrete (RC) beams were collected from the literature, in which the key variables were the reinforcement ratio, the presence of shear reinforcement, and section shape. The advantages are clearly shown in the shear stresses distributions being accurately described and the global load-displacement relations being successfully obtained and matching well with various test results. The proposed model shows satisfactory descriptions of the monotonic load-displacement response of the RC beams failing in multiple modes that vary from diagonal-tension to flexural-compression. In addition, more accurate and reliable information of sectional responses including sectional shear deformation and stresses is collected, leading to better prediction of a potential shear failure mode. Finally, the advantages of the proposed model are demonstrated by comparing the analysis results of an RCT-beam by using the different shear assumptions that include the constant and parabolic shear strains, constant shear flow, and the proposed shear stress function.

scholarly journals Determining the Shear Capacity of Steel Beams with Corrugated Webs by Using Optimised Regression Learner Techniques

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2364
Author(s):  
Ahmed S. Elamary ◽  
Ibrahim B. M. Taha
Keyword(s):  
Shear Stress ◽  
Gaussian Process Regression ◽  
Shear Capacity ◽  
Vertical Shear ◽  
Steel Beams ◽  
Test Results ◽  
Output Factor ◽  
Proposed Model ◽  
Corrugated Webs ◽  
Steel Grades

The use of corrugated webs increases web shear stability and eliminates the need for transverse stiffeners in steel beams. Optimised regression learner techniques (ORLTs) are rarely used for calculating shear capacity in steel beam research. This study proposes a new approach for calculating the maximum shear capacity of steel beams with trapezoidal corrugated webs (SBCWs) by using ORLTs. A new shear model is proposed using ORLTs in accordance with plate buckling theory and previously developed formulas for predicting the shear strength of SBCWs. The proposed ORLT models are implemented using the regression learner toolbox of MATLAB software (2020b). The available data of more than 125 test results from different specimens prepared by previous researchers are used to create the model. In this study, web geometry and relevant web steel grades determine the shear capacity of SBCWs. Four regression methods are adopted. Results are compared with those of an artificial neural network model. The model output factor represents the ratio of the web vertical shear stress to the normalised shear stress. Shear capacity can be estimated on the basis of the resulting factor from the model. The proposed model is verified using two methods. In the first method, a series of tests are performed by the authors. In the second method, the results of the model are compared with the shear values obtained experimentally by other researchers. On the basis of the test results of previous studies and the current work, the proposed model provides an acceptable degree of accuracy for predicting the shear capacity of SBCWs. The results obtained using Gaussian process regression are the most appropriate because its recoded mean square error is 0.07%. The proposed model can predict the shear capacity of SBCWs with an acceptable percentage of error. The recoded percentage of error is less than 5% for 93% of the total specimens. By contrast, the maximum differential obtained is ±10%, which is recorded for 3 out of 125 specimens.

Punching Shear Design Method of Voided Slabs

2017 ◽  
Vol 754 ◽  
pp. 333-336
Author(s):  
Joo Hong Chung ◽  
Hyun Ki Choi ◽  
Chang Sik Choi ◽  
Hyung Suk Jung
Keyword(s):  
Finite Element Analysis ◽  
Shear Strength ◽  
Design Method ◽  
Fe Analysis ◽  
Punching Shear ◽  
Test Results ◽  
Sectional Area ◽  
Element Analysis ◽  
Cross Sectional ◽  
Shear Design

This study presents punching shear design method of voided slab in accordance with arrangement of voids around columns. According to previous studies, the slab-column connection of voided slabs is weaker than that of the solid slab due to the lack of cross-sectional area of concrete by voids. In this study, it is assumed that the arrangement of voids exert influence on the punching shear strength of voided slabs. To verify the assumption, finite element analysis was conducted related with previous test results. The variable of FE analysis was a distance between voids and column face. Based on FE analysis and test results including previous studies, punching shear design method is suggested which can consider the arrangement of voids around columns. The suggested design method is based on the punching shear design method in ACI-318. As a result, it can predict the punching shear strength of voided slabs according to arrangement of voids around column.

scholarly journals Experimental investigations of punching shear concrete slabs with different types of transverse reinforcement

2014 ◽  
Vol 13 (3) ◽  
pp. 193-200
Author(s):  
Tadeusz Urban ◽  
Łukasz Krawczyk ◽  
Michał Gołdyn
Keyword(s):  
Load Capacity ◽  
Punching Shear ◽  
Experimental Program ◽  
Experimental Investigations ◽  
Concrete Slabs ◽  
Transverse Reinforcement ◽  
Shear Load ◽  
Test Results ◽  
Different Types ◽  
Flexural Reinforcement

The results of support zone thick concrete slabs experimental investigation are presented in the paper. The experimental program consisted of 4 square reinforced concrete flat models to 1:2 scale made of the same concrete with the same dimensions and the same flexural reinforcement. The aim of tests was proved the influence of different transverse reinforcement types on punching shear load capacity. One of the models was a comparative slab made without transverse reinforcement. In the other slabs three types of transverse reinforcement were used: typical stirrups enclosing flexure reinforcement, stirrups situated between flexure reinforcement and ladders. The test results show a few percent difference in load capacity between models with transverse reinforcement, the most effective were typical stirrups enclosing the main reinforcement.

Reinforced concrete slab-column edge connections with shear studs

2000 ◽  
Vol 27 (2) ◽  
pp. 338-348 ◽  
Author(s):  
Ehab F El-Salakawy ◽  
Maria Anna Polak ◽  
Monir H Soliman
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Concrete Slab ◽  
Punching Shear ◽  
Test Results ◽  
Shear Reinforcement ◽  
Reinforced Concrete Slab ◽  
Test Parameters ◽  
Flexural Reinforcement ◽  
Large Scale Tests

The paper reports the results of an experimental investigation on the influence of shear studs on the behaviour of reinforced concrete slab-column edge connections with openings. The test parameters were the location of openings around the column, the size of openings, and the existence of shear reinforcement. The objective of the paper is to present and discuss the results of large-scale tests on slabs with shear stud reinforcement and compare these test results with those of tests on identical slabs but without shear reinforcement. All tested slabs contained same amounts of typical flexural reinforcement (ACI 318-95 and CSA A23.3-94). The presented test results can be used for studying the behaviour of slab-column connections and for calibration of the predictive models.Key words: reinforced concrete, edge connections, flat concrete plates, punching shear, shear strength, openings, failure, shear studs, shear reinforcement.

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